Today, it has been possible to edit an image taken by a camera while watching it through a monitor using a computer so as to make a home page or a presentation material, output the edited image to an output device such as a printer, or store it in a hard disk drive or a compact disc.
For example, it has been possible to make a home page using an image taken by a camera over the Internet as connected, prepare various reports by inserting the image taken, and make an electronic album with photos in commemoration of graduation and marriage or store them in a record medium such as a diskette.
That is to say, a conventional camera is constructed of a lens for magnifying and penetrating a light source of an object; a charge coupled device (CCD) for converting a light signal of the object into an electric signal; a noise canceller for cancelling a noise of the electric signal; a digital signal processor (DSP) for processing the signal whose noise has been cancelled by the noise canceller into the image data; a main controller for operating an outputted signal of the digital signal processor (DSP) and controlling the entire system; a memory for storing the information of the main controller and the entire system; a decoder/selector for inputting external image signals from a plurality of cameras and selecting and outputting desired image signals; an image signal compressor for compressing an image signal; a RS-232C port connected to a computer for outputting an image signal stored in the memory; an Ethernet connected to a network line on which a control signal is transmitted and received; and a power supply for converting a voltage inputted from an AC adapter into various levels of voltage used in the camera and supplying it.
In the case of the conventional camera constructed as described above, the image signal taken by the camera is transmitted to the computer through a cable for data transmission as connected to the RS-232C port, and the image signal stored in the computer memory is also transmitted to another user's computer to which it is intended to be transmitted through the transmitting device over a commercial communication network and the Internet.
Further, a signal to control the camera in the computer is transmitted to the Ethernet of the camera through the network line.
In order to transmit the image signal of the camera to an external device, a cable for data transmission and a network cable should be separately installed.
Also, in the case of CCTV, a lot of cables should be installed in order to transmit image signals between a camera installed in a distant place and a monitoring center.
Thus, it is inconvenient to install cables and maintain the installed cables. Further, there is a problem to expend a high cost for installation of cables.
Korean patent application No. 10-2000-0032364 (entitled CAMERA HAVING A POWER LINE COMMUNICATION (PLC) MODEM) filed on Jun. 13, 2000 was suggested to solve the above problems with the conventional camera.
The suggested camera is a camera capable of transmitting and receiving image signals and control signals to and from the computer, wherein a power line communication modem for transmitting the image signal of the camera to the computer through the power line and the control signal of the computer to the camera through the power line is connected to an output end of the camera so that data may be transmitted over the power line without a separate line for data transmission.
However, in the case of the camera having the conventional power line communication (PLC) modem, the power line communication modem should be separately installed in the transmitting side and the receiving side respectively, and as a result, there are disadvantages that its configuration as well as operation for signal conversion becomes complicated.
Meanwhile, in a cable broadcasting system, a transmitting station transmits a broadcasting signal including a voice signal and an image signal to a receiving station on a cable. Thus, the cable to transmit the broadcasting signal to the receiving station should be installed to each broadcasting receiver in order to operate such cable broadcasting system.
As said above, since a leased cable to connect between the transmitting station and the receiving station should be installed in the conventional cable broadcasting system, a high equipment cost is required to operate the cable broadcasting system, which causes a problem of deteriorating economical efficiency.
So, Korean patent application No. 10-2000-0078610 (entitled CABLE BROADCASTING SYSTEM USING A power line) filed on Dec. 19, 2000 was suggested. The suggested system comprises a transmitting station for transmitting a broadcasting signal including a voice signal and an image signal through a power line; and a receiving station for receiving a broadcasting signal transmitted from the transmitting station through the power line and outputting it confirmably.
Wherein the transmitting station comprises a signal generator for generating a broadcasting signal including the voice signal and the image signal which are to be provided to the broadcasting receiver; a modulator for modulating the broadcasting signal applied from the signal generator into a given frequency different from an alternating current power frequency; and an alternating current power cut-off unit for cutting off the alternating current power applied from the power line so that it may not be applied to the modulator and transmitting the broadcasting signal applied from the modulator to the power line; and
the receiving station comprises an alternating current power cut-off unit for cutting off an alternating current power applied from the power line and transmitting the broadcasting signal applied from the power line; and a demodulator for demodulating the broadcasting signal applied from the alternating current power cut-off unit, extracting the voice signal and the image signal and outputting them to a receiving device.
However, the conventional cable broadcasting system using the power line has shortcomings that the configuration of the modulator and the demodulator becomes complicated and modulating and demodulating operations are complicated.